Self-righteousness can feed upon doctrines — as well as upon works! - John Newton

Jesus did not tell parables to confirm well-known truths, but rather to shatter well-known truths.

Indeed, every sin, in its own nature, has a tendency towards a final apostacy; but there is a provision in the covenant of grace, and the Lord, in His own time, returns to convince, humble, pardon, comfort, and renew the soul. He touches the rock, and the waters flow. By repeated experiments and exercises of this sort (for this wisdom is seldom acquired by one or a few lessons), we begin at length to learn that we are nothing, have nothing, can do nothing, but sin. And thus we are gradually prepared to live more out of ourselves, and to derive all our sufficiency of every kind from Jesus, the fountain of grace.

The midsummer sun shines but dim, The fields strive in vain to look gay; But when I am happy in Him December's as pleasant as May.